Optical fiber structure

ABSTRACT

An optical fiber structure includes a first fiber array and a second fiber array, which are placed one on the other. For example, the first fiber array includes a substrate having four V-shaped grooves and four first optical fibers, the output ends of which are linearly arranged and fixed to the grooves. The second fiber array includes a substrate having four V-shaped grooves and four second optical fibers, the output ends of which are linearly arranged and fixed to the grooves. The first optical fiber has a taper portion, in which the core diameter decreases along an optical axis, and the core diameter and the outer diameter of the first optical fiber at the tip of the taper portion thereof are 60 μm and 80 μm, respectively. The core diameter and the outer diameter of the second optical fiber are 105 μm and 125 μm, respectively.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical fiber structure in which aplurality of optical fiber arrays, each including a plurality ofmultimode optical fibers, are placed one on another.

2. Description of the Related Art

Conventionally, laser light has been used in the fields of printing andprocessing. For example, in production of printing blocks as describedin U.S. Pat. No. 6,857,365, the laser light is used to process materialsto produce print blocks. In recent years, high-output semiconductorlasers have been developed. Further, optical fiber structures thattransmit high-output laser light, which is output from the high-outputsemiconductor lasers, through fibers and output the transmitted lightare known. Further, in the field of optical fiber structures that areused in processing as described above, multicore-type optical fiberstructures in which a plurality of optical fibers are fixed in such amanner that one-side ends thereof are arranged in line form or in blockform are being developed to improve the processing efficiency.

When the laser light is used to process the print blocks as described inU.S. Pat. No. 6,857,365, there are cases in which laser light that has asmall beam diameter is desirable and cases in which laser light that hasa large beam diameter is desirable, depending on processing conditions.For example, when a highly-precise process should be carried out, thelaser light that has a small diameter is desirable. In contrast, when aso-called solid processing should be performed, in other words, when theentire area of a certain area should be processed uniformly, the laserlight that has a large diameter is desirable. However, in theconventional multicore-type optical fiber structure, there is a problemthat it is impossible to change the beam diameter based on theprocessing conditions, because the multicore-type optical fiberstructure includes a plurality of same optical fibers, which outputbeams having the same beam diameter. Meanwhile, there is an apparatusthat changes the beam diameter of laser light by a special opticalsystem provided in a later stage. However, there is a problem that suchan optical system tends to be complex.

SUMMARY OF THE INVENTION

In view of the foregoing circumstances, it is an object of the presentinvention to provide an optical fiber structure that has simplestructure, but that can output light beams having different beamdiameters from each other.

An optical fiber structure according to the present invention is anoptical fiber structure comprising:

a first optical fiber array including a plurality of optical fibers, theoutput ends of which are linearly arranged; and

a second optical fiber array including a plurality of optical fibers,the output ends of which are linearly arranged, wherein the firstoptical fiber array and the second optical fiber array are placed one onthe other, and wherein the optical fibers in the first optical fiberarray and the second optical fiber array include at least one firstoptical fiber, the core diameter of which at the output end thereof is afirst core diameter, and at least one second optical fiber, the corediameter of which at the output end thereof is a second core diameter,and wherein the first core diameter is different from the second corediameter, and wherein at least one of the first optical fiber and thesecond optical fiber has a taper portion, the core diameter of whichdecreases or increases along an optical axis.

The expression “the optical fibers in the first optical fiber array andthe second optical fiber array include at least one first optical fiber,the core diameter of which at the output end thereof is a first corediameter” means that at least one of the optical fibers is the firstoptical fiber. Further, the expression “the optical fibers in the firstoptical fiber array and the second optical fiber array include . . . atleast one second optical fiber, the core diameter of which at the outputend thereof is a second core diameter, and wherein the first corediameter is different from the second core diameter” means that at leastone of the optical fibers is a second optical fiber.

Further, when the first optical fiber array includes a plurality offirst optical fibers arranged therein, the second optical fiber arraymay include a plurality of second optical fibers arranged therein.

Alternatively, each of the first optical fiber array and the secondoptical fiber array may include at least one first optical fiber and atleast one second optical fiber arranged therein. Further, each of thefirst optical fibers and the second optical fibers may be arranged insuch a manner that the arrangement in the second optical fiber array isin reverse order to the order of arrangement in the first optical fiberarray.

The expression “the arrangement in the second optical fiber array is inreverse order to the order of arrangement in the first optical fiberarray” means that when the second optical fiber array is placed upsidedown, the arrangement of the optical fibers in the second optical fiberbecomes the same as the arrangement of the optical fibers in the firstoptical fiber array.

When the first optical fiber array includes the at least one firstoptical fiber arranged in a half of the first optical fiber array andthe at least one second optical fiber arranged in the other half of thefirst optical fiber array, the second optical fiber array may includethe at least one second optical fiber arranged in a half of the secondoptical fiber array and the at least one first optical fiber arranged inthe other half of the second optical fiber array.

When the at least one first optical fiber and the at least one secondoptical fiber in the first optical fiber array are alternately arrangedone by one, the at least one second optical fiber and the at least onefirst optical fiber in the second optical fiber array may be alternatelyarranged one by one.

Further, the first optical fiber arranged in the first optical fiberarray and the second optical fiber arranged in the second optical fiberarray may face each other, and the second optical fiber arranged in thefirst optical fiber array and the first optical fiber arranged in thesecond optical fiber array may face each other.

The expression “the first optical fiber arranged in the first opticalfiber array and the second optical fiber arranged in the second opticalfiber array face each other, and the second optical fiber arranged inthe first optical fiber array and the first optical fiber arranged inthe second optical fiber array face each other” means that the firstoptical fiber arranged in the first optical fiber array and the secondoptical fiber arranged in the second optical fiber array are linearlyaligned in a direction that is substantially perpendicular to thearrangement direction (extending direction) of the optical fiber arraysand that the second optical fiber arranged in the first optical fiberarray and the first optical fiber arranged in the second optical fiberarray are linearly aligned in a direction that is substantiallyperpendicular to the arrangement direction of the optical fiber arrays.The first optical fibers and the second optical fibers may be in directcontact with each other. Alternatively, a pressure plate or the like maybe inserted between the first optical fiber and the second opticalfiber.

In the optical fiber structure according to the present invention, atransparent member for protecting the end surfaces of the optical fibersmay be attached to the surfaces of the output ends of the optical fibersby optical contact.

Further, an anti-reflection coating may be provided on the output sideof the transparent member for protecting the end surfaces of the opticalfibers.

Further, the power of light that is output from each of the opticalfibers may be greater than or equal to 1 W.

The optical fiber structure according to the present invention is anoptical fiber structure comprising:

a first optical fiber array including a plurality of optical fibers, theoutput ends of which are linearly arranged; and

a second optical fiber array including a plurality of optical fibers,the output ends of which are linearly arranged, wherein the firstoptical fiber array and the second optical fiber array are placed one onthe other, and wherein the optical fibers in the first optical fiberarray and the second optical fiber array include at least one firstoptical fiber, the core diameter of which at the output end thereof is afirst core diameter, and at least one second optical fiber, the corediameter of which at the output end thereof is a second core diameter,and wherein the first core diameter is different from the second corediameter, and wherein at least one of the first optical fiber and thesecond optical fiber has a taper portion, the core diameter of whichdecreases or increases along an optical axis. Therefore, the corediameter of the first optical fiber at the output end thereof or thecore diameter of the second optical fiber at the output end thereof canbe easily changed to a desirable core diameter. Further, it is possibleto output light beams that have different beam diameters from each otherfrom a single optical fiber structure that has simple structure withoutproviding a complicated optical system, which was necessary inconventional techniques. Further, since the optical fiber has the taperportion, the core diameter of which decreases or increases along anoptical axis, it is possible to easily change the core diameter at theoutput end to a desirable core diameter. Hence, it is possible to obtainan optical fiber structure that can output a light beam having anarbitrary beam diameter.

Further, when the first optical fiber array includes a plurality offirst optical fibers arranged therein and the second optical fiber arrayincludes a plurality of second optical fibers arranged therein, if auser wants to use a light beam output from the first optical fiber,he/she can use the first optical fiber array. Alternatively, if the userwants to use a light beam output from the second optical fiber, he/shecan use the second optical fiber array. Therefore, the convenience ofthe optical fiber structure is improved.

When each of the first optical fiber array and the second optical fiberarray includes at least one first optical fiber and at least one secondoptical fiber arranged therein, and each of the first optical fibers andthe second optical fibers is arranged in such a manner that thearrangement in the second optical fiber array is in reverse order to theorder of arrangement in the first optical fiber array, two fiber arraysin which the optical fibers are arranged in the same manner may beproduced. Then, one of the two fiber arrays may be placed in an ordinarydirection, and the other fiber array may be placed upside down. Further,the two fiber arrays may be placed one on the other to produce theoptical fiber structure. Hence, simple and low-cost production of theoptical fiber structure becomes possible.

Further, when the first optical fiber arranged in the first opticalfiber array and the second optical fiber arranged in the second opticalfiber array face each other and the second optical fiber arranged in thefirst optical fiber array and the first optical fiber arranged in thesecond optical fiber array face each other, the first optical fiber andthe second optical fiber can carry out processing with respect to thesame pixel, for example, in print processing or the like. Hence, theusability and convenience of the optical fiber structure is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the structure of an opticalfiber structure according to a first embodiment of the presentinvention;

FIG. 2 is a schematic diagram illustrating the structure of an opticalfiber;

FIG. 3 is a schematic diagram illustrating the structure of an opticalfiber array;

FIG. 4 is a schematic diagram illustrating the structure of an opticalfiber;

FIG. 5 is a schematic diagram illustrating the structure of an opticalfiber array;

FIG. 6A is a schematic diagram illustrating the structure of anotheroptical fiber structure;

FIG. 6B is a schematic diagram illustrating the structure of an opticalfiber structure according to a second embodiment of the presentinvention;

FIG. 7 is a schematic diagram illustrating the structure of an opticalfiber structure according to a third embodiment of the presentinvention;

FIG. 8 is a schematic diagram illustrating the structure of an opticalfiber array;

FIG. 9A is a schematic diagram illustrating the structure of anotheroptical fiber structure;

FIG. 9B is a schematic diagram illustrating the structure of an opticalfiber structure according to a fourth embodiment of the presentinvention;

FIG. 10 is a schematic diagram illustrating the structure of an opticalfiber structure according to a fifth embodiment of the presentinvention;

FIG. 11 is a schematic diagram illustrating the structure of an opticalfiber array; and

FIG. 12 is a schematic diagram illustrating the structure of an opticalfiber structure according to a sixth embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An optical fiber structure according to a first embodiment of thepresent invention will be described with reference to the attacheddrawings. FIG. 1 is a schematic diagram illustrating the structure of anoptical fiber structure 100.

As illustrated in FIG. 1, the optical fiber structure 100 includes afirst fiber array (first optical fiber array) 110, a second fiber array(second optical fiber array) 120 and a pressure plate 130. The firstfiber array 110 includes a substrate 111 having four V-shaped grooves112 and four optical fibers 10, the ends of which are fixed onto thesubstrate 111 having the four V-shaped grooves. The second fiber array120 includes a substrate 121 having four V-shaped grooves 122 and fouroptical fibers 20, the ends of which are fixed onto the substrate 121having the four V-shaped grooves. The first fiber array 110 and thesecond fiber array 120 are placed one on the other with the pressureplate 130 therebetween in such a manner that the optical fibers 10 andthe optical fibers 20 face each other, and the positions of the firstfiber array 110 and the second fiber array 120 are fixed.

As illustrated in FIG. 2, the optical fiber 10 is a multimode fiberhaving a core 12 and a cladding (a clad or a cladding layer) 14. Theoptical fiber 10 includes an ordinary portion 16 and a taper portion 18.The core diameter of the ordinary portion 16 is 105 μm, and the outerdiameter of the fiber at the ordinary portion 16 is 125 μm. The taperportion 18 is formed at the tip of the ordinary portion 16. In the taperportion 18, the core diameter and the outer diameter of the fiberdecrease along an optical axis. Further, at the leading end of the taperportion 18, in other words, at the output end 11 a of the optical fiber10, the core diameter is 60 μm, and the outer diameter of the fiber is80 μm. Further, a polished end surface 13 a of the core is exposed atthe output end 11 a of the optical fiber 10. When light beam B1, whichhas propagated through the optical fiber 10, is output from the outputend 11 a of the optical fiber 10, the beam diameter L1 of the light beamB1 at the output end 11 a is the same as the core diameter, which is 60μm. As illustrated in FIG. 3, the output ends 11 a of four opticalfibers 10 are fixed into the V-shaped grooves 112 in the substrate 111having the V-shaped grooves 112, respectively, in such a manner that theoutput ends 11 a of the optical fibers 10 are linearly arranged at theends of the V-shaped grooves 112 of the substrate 111 having theV-shaped grooves 112. The optical fibers 10 are fixed into the V-shapedgrooves 112 with an ultraviolet-setting resin (a UV-setting resin, aUV-curable resin or an ultraviolet-curable resin), a thermosettingadhesive resin (a thermosetting resin or a thermally curable resin) orthe like.

As illustrated in FIG. 4, the optical fiber 20 is a multimode fiberhaving a core 22 and a cladding (a clad or a cladding layer) 24. Thediameter of the core 22 is 105 μm, and the outer diameter of the fiberis 125 μm. Further, a polished end surface 23 a of the core is exposedat the output end 21 a of the optical fiber 20. When light beam B2,which has propagated through the optical fiber 20, is output from theoutput end 21 a of the optical fiber 20, the beam diameter L2 of thelight beam B2 is the same as the core diameter, which is 105 μm. Asillustrated in FIG. 5, the output ends 21 a of the four optical fibers20 are fixed into the V-shaped grooves 122 in the substrate 121 havingthe V-shaped grooves 122, respectively, in such a manner that the outputends 21 a of the optical fibers 20 are linearly arranged at the ends ofthe V-shaped grooves 122 of the substrate 121 having the V-shapedgrooves 122. The optical fibers 20 are fixed into the V-shaped grooves122 with an ultraviolet-setting resin, a thermosetting adhesive resin orthe like.

The optical fiber structure 100 may be used, for example, as an opticalhead for processing print block plates (or to engrave print patterns onplates) or the like with laser light. In such a case, a high-outputsemiconductor laser having output power of 10 W or the like, which isnot illustrated, is connected to the input end of each of the opticalfibers 10 and the optical fibers 20, the input end being opposite to theoutput end thereof. Further, an optical system (not illustrated) forcondensing the light beam output from the optical fiber structure 100onto the plate for printing is arranged between the optical fiberstructure 100 and the plate for printing. It is possible to process theplate for printing by outputting laser light from a high-outputsemiconductor laser that is connected to a desirable optical fiber,which a user wants to use for the processing, while shifting the opticalfiber structure 100 and the plate for printing relative to each other inthe vertical direction of FIG. 1.

As described above, the beam diameter L1 of the light beam B1 at theoutput end 11 a of the optical fiber 10 is the same as the core diameterof the optical fiber 10, which is 60 μm. Further, the beam diameter L2of the light beam B2 at the output end 21 a of the optical fiber 20 isthe same as the core diameter of the optical fiber 20, which is 105 μm.The optical fiber structure 100, which has simple structure, can outputlight beams that have different beam diameters. For example, when it isdesirable to use a light beam that has a small diameter to carry outhighly precise processing or the like, the light beam output from theoptical fiber 10 is used. In contrast, when it is desirable to use alight beam that has a large diameter to carry out a so-called solidprocess (processing the entire area of a certain portion uniformly sothat no unprocessed area substantially remains after the processing) orthe like, the light beam output from the optical fiber 20 is used.Further, since the optical fiber 10 has the taper portion 18, the corediameter of which decreases along an optical axis, it is possible toeasily change the core diameter at the output end 11 a to a desirablecore diameter. Further, when fibers that have small diameters areprepared, if at least one of the fibers is used as the optical fiber 20,and at least one of the fibers is used as the optical fiber 10 byforming a taper portion, it is possible to use an optical beam that hasa small diameter and an optical beam that has an even smaller diameter.

Further, since the optical fibers 10 and the optical fibers 20 arearranged so as to face each other, it is possible to output light beamsthat have different beam diameters from each other for the same singlepixel, for example, in print processing or the like. Hence, the opticalfiber structure 100 is used even more usefully.

FIG. 6A illustrates an optical fiber structure 140, which is a modifiedexample of the present embodiment. When it is not necessary that theoptical fibers 10 and the optical fibers 20 are aligned in a directionperpendicular to the arrangement direction of each of the optical fiberarrays, the optical fibers 10 and the optical fibers 20 may be arrangedas in the optical fiber structure 140. In the optical fiber structure140, the optical fibers 10 and the optical fibers 20 are arranged asclosely as possible, thereby reducing the size of the optical fiberstructure.

Next, an optical fiber structure according to a second embodiment of thepresent invention will be described. FIG. 6B is a schematic diagramillustrating the structure of an optical fiber structure 150. Thestructure of the optical fiber structure 150 is similar to that of theoptical fiber structure 100, illustrated in FIG. 1, except that atransparent member 160 for protecting the end surface is provided at theoutput end surface in the optical fiber structure 150. Therefore, thesame reference numerals will be assigned to corresponding parts andelements, and the explanation thereof will be omitted.

As illustrated in FIG. 6B, the optical fiber structure 150 includes thefirst fiber array 110, the second fiber array 120, the pressure plate130 and the transparent member 160 for protecting the end surface. Thefirst fiber array 110 includes a substrate 111 having V-shaped groovesand four optical fibers 10, the ends of which are fixed onto thesubstrate 111. The second fiber array 120 includes the substrate 121having V-shaped grooves and four optical fibers 20, the ends of whichare fixed onto the substrate 121. The transparent member 160 forprotecting the end surface is attached to the output end 11 a of each ofthe optical fibers 10 and the output end 21 a of each of the opticalfibers 20 by optical contact.

The transparent member 160 is a rectangular plate made of quartz, and asurface 161 b of the transparent member 160 is coated with ananti-reflection coating 162. The surface 161 b is opposite to a surface161 a of the transparent member 160, the surface 161 a being in contactwith the output ends of the optical fibers.

As described above, the transparent member 160 for protecting the endsurfaces is attached to the output end of each of the optical fibers byoptical contact. Therefore, the light beam that has been output from theoutput end of each of the optical fibers is transmitted through thetransparent member 160, and output to the outside of the transparentmember 160 from the surface 161 b of the transparent member 160. Sincethe output end of each of the optical fibers is covered with thetransparent member, it is possible to prevent the output ends of theoptical fibers from being damaged by burning due to adhesion of dust orthe like thereto.

Further, when the light beam passes through the transparent member 160,the diameter of the light beam increases. Therefore, the density of thelight beam at the output position from the optical fiber structure 150to air, which is the surface 161 b in this embodiment, is lower than thedensity of the light beam output from the optical fiber structure inwhich the transparent member 160 is not provided. Therefore, thetransparent member 160 can prevent burning at the surface 161 b of thetransparent member 160. Further, the transparent member 160 can preventthe anti-reflection coating 162 that has been applied to the surface 161b of the transparent member 160 from being damaged. Further, thetransparent member 160 can reduce light that returns from the outputsurface of the light beam. Therefore, it is possible to prevent thelasers connected to the input ends of the optical fibers from beingdamaged.

Further, the optical fiber structure 140, illustrated in FIG. 6A, may bemodified in such a manner that a transparent member 160 is provided atthe output ends of the optical fibers, which output light beams.

Next, an optical fiber structure according to a third embodiment of thepresent invention will be described. FIG. 7 is a schematic diagramillustrating the structure of an optical fiber structure 200. In FIG. 7,the same reference numerals will be assigned to parts and elementscorresponding to those of the optical fiber structure 100, illustratedin FIG. 1, and the explanation thereof will be omitted.

As illustrated in FIG. 7, the optical fiber structure 200 includes afirst fiber array 210, a second fiber array 220 and a pressure plate230. The first fiber array 210 includes a substrate 211 having fourV-shaped grooves 212, two optical fibers 10 and two optical fibers 20,the ends of the two optical fibers 10 and the two optical fibers 20being fixed onto the substrate 211 having the V-shaped grooves. Thesecond fiber array 220 includes a substrate 221 having four V-shapedgrooves 222, two optical fibers 10 and two optical fibers 20, the endsof the two optical fibers 10 and the two optical fibers 20 being fixedonto the substrate 221. The first fiber array 210 and the second fiberarray 220 are placed one on the other, with the pressure plate 230therebetween, in such a manner that the optical fibers 10 and theoptical fibers 20 face each other, and fixed. In the first fiber array210, the two optical fibers 10 are arranged from the left side of thefirst fiber array 210 illustrated in FIG. 7. Further, the two opticalfibers 20 are arranged on the right side of the optical fibers 10.Meanwhile, in the second fiber array 220, the two optical fibers 20 arearranged from the left side of the second fiber array 220 illustrated inFIG. 7. Further, the two optical fibers 10 are arranged on the rightside of the optical fibers 20. Specifically, the arrangement of theoptical fibers in the first fiber array 210 and that of the opticalfibers in the second fiber array 220 are opposite to each other (inother words, in reveres order).

In the second fiber array 220, two optical fibers 10 and two opticalfibers 20 are arranged as illustrated in FIG. 8. The two optical fibers10 and the two optical fibers 20 are fixed into V-shaped grooves 222 ofthe substrate 221 having the V-shaped grooves, respectively, using anultraviolet setting resin, a thermosetting resin or the like. The twooptical fibers 10 and the two optical fibers 20 are fixed in such amanner that the output ends of the two optical fibers 10 and the twooptical fibers 20 are linearly arranged at the ends of the V-shapedgrooves 222 of the substrate 221 having the V-shaped grooves.

Further, FIG. 8 may be viewed as a diagram in which the first fiberarray 210, illustrated in FIG. 7, is placed upside down. In FIG. 8, twooptical fibers 10 and two optical fibers 20 are fixed into the V-shapedgrooves 212 of the substrate 211 having the V-shaped grooves,respectively, using an ultraviolet setting resin, a thermosetting resinor the like. The two optical fibers 10 and the two optical fibers 20 arefixed in such a manner that the output ends of the two optical fibers 10and the two optical fibers 20 are linearly arranged at the ends of theV-shaped grooves 212 of the substrate 211 having the V-shaped grooves.Specifically, the structure of the first fiber array 210 and that of thesecond fiber array 220 are the same.

The optical fiber structure 200 may be used, for example, as an opticalhead for processing plates for printing with a laser beam in a mannersimilar to the optical fiber structure 100. The optical fiber structure200 has advantageous effects similar to those of the optical fiberstructure 100. Further, the optical fiber structure 200 can be obtainedby producing two fiber arrays that have the same structure and byplacing the two fiber arrays one on the other. Therefore, the opticalfiber structure 200 can be produced easily and at low cost. Further, theouter diameter of the optical fiber 10 and that of the optical fiber 20are different from each other. Therefore, the heights of the opticalfibers 10 and the optical fibers 20 in the first fiber array 210, theheights at positions opposite to the substrate 211 having the V-shapedgrooves, and the heights of the optical fibers 10 and the optical fibers20 in the second fiber array 220, the heights at positions opposite tothe substrate 221 having the V-shaped grooves, are opposite to eachother. In other words, the heights of the optical fibers facing eachother are opposite to each other (when the height of an optical fiber ishigh, the optical fiber facing the optical fiber is low, and viceversa). Therefore, when the first fiber array 210 and the second fiberarray 220 are placed one on the other, positioning can be performedeasily.

An optical fiber structure 240, which is a modified example of thepresent embodiment, is illustrated in FIG. 9A. When it is not necessarythat the optical fibers 10 and the optical fibers 20 are aligned in adirection perpendicular to the arrangement direction of each of theoptical fiber arrays, the optical fibers 10 and the optical fibers 20may be placed as arranged in the optical fiber structure 240. In theoptical fiber structure 240, the optical fibers 10 and the opticalfibers 20 are arranged as closely as possible, thereby reducing the sizeof the optical fiber structure.

Next, an optical fiber structure 250 according to a fourth embodiment ofthe present invention will be described with reference to FIG. 9B. FIG.9B is a schematic diagram illustrating the structure of the opticalfiber structure 250. In the optical fiber structure 250, the output endof the optical fiber structure 200, illustrated in FIG. 7, is placed inoptical contact with the transparent member 160 for protecting the end,illustrated in FIG. 6B. The action and the advantageous effect of thetransparent member 160 are substantially similar to those of thetransparent member 160 in the optical fiber structure 150 illustrated inFIG. 6B. Therefore, detailed description on the transparent member 160will be omitted.

Next, an optical fiber structure according to a fifth embodiment of thepresent invention will be described. FIG. 10 is a schematic diagramillustrating the structure of an optical fiber structure 300. In FIG.10, the same reference numerals as those assigned to the correspondingelements in the optical fiber structure 100, illustrated in FIG. 1, willbe assigned to the parts and elements of the optical fiber structure300, and detailed descriptions thereof will be omitted.

As illustrated in FIG. 10, the optical fiber structure 300 includes afirst fiber array 310, a second fiber array 320 and a pressure plate330. The first fiber array 310 includes a substrate 311 having fourV-shaped grooves 312, two optical fibers 10 and two optical fibers 20.The two optical fibers 10 and the two optical fibers 20 are alternatelyarranged, and the output ends thereof are fixed to the substrate 311having the V-shaped grooves. The second fiber array 320 includes asubstrate 321 having four V-shaped grooves, two optical fibers 10 andtwo optical fibers 20. The two optical fibers 10 and the two opticalfibers 20 are alternately arranged, and the output ends thereof arefixed onto the substrate 321 having the V-shaped grooves. Further, thefirst fiber array 310 and the second fiber array 320 are placed one onthe other, with the pressure plate 330 therebetween, in such a mannerthat the optical fibers 10 and the optical fibers 20 face each other,and fixed. In other words, the optical fiber 10 in the first fiber array310 faces the optical fiber 20 in the second fiber array 320, and theoptical fiber 20 in the first fiber array 310 faces the optical fiber 10in the second fiber array 320. In the first fiber array 310, the orderof arrangement of the optical fibers is the optical fiber 10, theoptical fiber 20, the optical fiber 10, and the optical fiber 20 fromthe left side of FIG. 10. Meanwhile, in the second fiber array 320, theorder of arrangement of the optical fibers is the optical fiber 20, theoptical fiber 10, the optical fiber 20, and the optical fiber 10 fromthe left side of FIG. 10. In other words, the optical fibers in thefirst fiber array 310 are arranged in reverse order to the order ofarrangement of the optical fibers in the second fiber array 320.

As illustrated in FIG. 11, in the second fiber array 320, the twooptical fibers 10 and the two optical fibers 20 are fixed in such amanner that the output ends of the two optical fibers 10 and the twooptical fibers 20 are linearly arranged at the ends of the V-shapedgrooves 322 of the substrate 321 having the V-shaped grooves. Theoptical fibers are fixed into the V-shaped grooves 322, respectively,using an ultraviolet setting resin, a thermosetting resin or the like.

Further, FIG. 11 may be viewed as a diagram in which the first fiberarray 310, illustrated in FIG. 10, is placed upside down. In FIG. 11,the two optical fibers 10 and the two optical fibers 20 are fixed intothe V-shaped grooves 312 of the substrate 311 having the V-shapedgrooves, respectively, using an ultraviolet setting resin, athermosetting resin or the like. The two optical fibers 10 and the twooptical fibers 20 are fixed in such a manner that the output ends of thetwo optical fibers 10 and the two optical fibers 20 are linearlyarranged at the ends of the V-shaped grooves 312 of the substrate 311having the V-shaped grooves. Specifically, the structure of the firstfiber array 310 and that of the second fiber array 320 are the same.

The optical fiber structure 300 may be used, for example, as an opticalhead for processing plates for printing with a laser beam in a mannersimilar to the optical fiber structure 100. The optical fiber structure300 has advantageous effects similar to those of the optical fiberstructure 100. Further, the optical fiber structure 300 can be obtainedby producing two fiber arrays that have the same structure and byplacing the two fiber arrays one on the other. Therefore, the opticalfiber structure 300 can be produced easily. Further, the outer diameterof the optical fiber 10 and that of the optical fiber 20 are differentfrom each other. Therefore, the projections/depressions of the firstfiber array 310, the projections/depressions positioned opposite to thesubstrate 311 having the V-shaped grooves, and theprojections/depressions of the second fiber array 320, theprojections/depressions positioned opposite to the substrate 321 havingthe V-shaped grooves, are opposite to each other (a projection faces adepression, and vice versa). Therefore, when the first fiber array 310and the second fiber array 320 are placed one on the other, positioningcan be performed easily. Further, for example, when so-called solidprocessing is performed, in other words, when the entire area of acertain portion is processed uniformly using a multiplicity of lightbeams having large diameters, since a contact area between the opticalfibers is small, it is possible to prevent the ends of the opticalfibers from being damaged by heat.

Further, in the optical fiber structure 300, when it is not necessarythat the optical fibers 10 and the optical fibers 20 are aligned in adirection perpendicular to the arrangement direction of each of theoptical fiber arrays, the optical fiber structure 300 may be modified insuch a manner that the optical fibers 10 and the optical fibers 20 areplaced as closely as possible. Further, in the modified example, thetransparent member 160 may be attached to the output ends of the lightbeams.

In the above example, the optical fibers are alternately arranged one byone. Alternatively, when a large number of optical fibers should bearranged, the optical fibers may be alternately arranged two by two (intwos), or three by three (in threes).

In each of the aforementioned embodiments, four optical fibers arearranged in each of the optical fiber arrays. However, the number of theoptical fibers is not limited to four. For example, 16, 32 or 64 opticalfibers may be arranged in each of the optical fiber arrays.

In each of the aforementioned embodiments, an optical fiber having ataper portion, the core diameter of which decreases along an opticalaxis, is used as the optical fiber 10. Alternatively, for example, anordinary optical fiber may be used as the optical fiber 10 and anoptical fiber having a taper portion, the core diameter of whichincreases along an optical axis, may be used as the optical fiber 20.Alternatively, an optical fiber having a taper portion, the corediameter of which decreases along an optical axis, may be used as theoptical fiber 10 and an optical fiber having a taper portion, the corediameter of which increases along an optical axis, may be used as theoptical fiber 20.

1. An optical fiber structure comprising: a first optical fiber arrayincluding a plurality of optical fibers, the output ends of which arelinearly arranged; and a second optical fiber array including aplurality of optical fibers, the output ends of which are linearlyarranged, wherein the first optical fiber array and the second opticalfiber array are placed one on the other, wherein the optical fibers inthe first optical fiber array and the second optical fiber array includeat least one first optical fiber, the core diameter of which at theoutput end thereof is a first core diameter, and at least one secondoptical fiber, the core diameter of which at the output end thereof is asecond core diameter, wherein the first core diameter is different fromthe second core diameter, and wherein at least one of the first opticalfiber and the second optical fiber has a taper portion, the corediameter of which decreases or increases along an optical axis, whereineach of the first optical fiber array and the second optical fiber arrayincludes at least one first optical fiber and at least one secondoptical fiber arranged therein, wherein each of the first optical fibersand the second optical fibers is arranged in such a manner that an orderof arrangement in the second optical fiber array is reverse to an orderof arrangement in the first optical fiber array and wherein: the atleast one first optical fiber comprises a plurality of first opticalfibers, the at least one second optical fiber comprises a plurality ofsecond optical fibers, the first optical fiber array includes at leastone of the first optical fibers arranged in a half of the first opticalfiber array and the at least one of the second optical fibers arrangedin another half of the first optical fiber array, and the second opticalfiber array includes at least one other of the second optical fibersarranged in a half of the second optical fiber array and at least oneother of the first optical fibers arranged in another half of the secondoptical fiber array.
 2. An optical fiber structure, as defined in claim1, wherein a transparent member for protecting the end surfaces of theoptical fibers is attached to the surfaces of the output ends of theoptical fibers by optical contact.
 3. An optical fiber structure, asdefined in claim 2, wherein an anti-reflection coating is provided onthe output side of the transparent member for protecting the endsurfaces of the optical fibers.
 4. An optical fiber structure, asdefined in claim 1, wherein the power of light that is output from eachof the optical fibers is greater than or equal to 1 W.
 5. An opticalfiber structure, as defined in claim 1, wherein an end face, of the atleast one of the first optical fiber and the second optical fiber havingthe taper portion, is perpendicular to an optical axis, of the at leastone of the first optical fiber and the second optical fiber having thetaper portion.
 6. An optical fiber structure comprising: a first opticalfiber array including a plurality of optical fibers, the output ends ofwhich are linearly arranged; and a second optical fiber array includinga plurality of optical fibers, the output ends of which are linearlyarranged, wherein the first optical fiber array and the second opticalfiber array are placed one on the other, wherein the optical fibers inthe first optical fiber array and the second optical fiber array includeat least one first optical fiber, the core diameter of which at theoutput end thereof is a first core diameter, and at least one secondoptical fiber, the core diameter of which at the output end thereof is asecond core diameter, wherein the first core diameter is different fromthe second core diameter, wherein at least one of the first opticalfiber and the second optical fiber has a taper portion, the corediameter of which decreases or increases along an optical axis, whereineach of the first optical fiber array and the second optical fiber arrayincludes at least one first optical fiber and at least one secondoptical fiber arranged therein, wherein each of the first optical fibersand the second optical fibers is arranged in such a manner that an orderof arrangement in the second optical fiber array is reverse to an orderof arrangement in the first optical fiber array; and wherein: the atleast one first optical fiber comprises a plurality of first opticalfibers, the at least one second optical fiber comprises a plurality ofsecond optical fibers, the first optical fiber array includes one of thefirst optical fibers and one of the second optical fibers are inalternately arranged one by one, and the second optical fiber arrayincludes another of the second optical fibers and another of the firstoptical fibers alternately arranged one by one.